In Biddle Lecture, Ayres says race-motivated police stops are under-reported

Delivering the Francis Biddle Memorial Lecture at HLS on November 12, Yale Law School Professor Ian Ayres applied his unique brand of number crunching to evaluate statistical models that have been employed to measure police racial bias in decisions to stop vehicles and pedestrians.

In a talk entitled “A New Test for Race Discrimination: Lessons from a study of the LAPD,” Ayres challenged bias-measuring formulas used by other researchers, saying they include unnecessary variables that lead to the understatement of disparate-impact racial bias. (Watch a webcast )

Citing a study he coauthored with Jonathan Borowsky ’11 evaluating stops of minority drivers and pedestrians by the Los Angeles Police Department, Ayres said the data showed overwhelmingly that the LAPD stopped minority suspects at a much higher rate than has been reported by researchers whose studies were designed to include more variables.

“While statisticians testing for disparate racial treatment are normally worried about ‘omitted variable’ bias, when testing for unjustified disparate impacts, it is often necessary to be more worried about ‘included variable bias,’” Ayres and Borowsky wrote in the study. “Including controls for non-race factors that do not represent legitimate justifications for racial disparities can bias the estimate of whether a decision maker’s policies produced an unjustified disparate impact.”

Ayres is one of the most widely cited and prolific law professors of his generation and has published nine books and more than 100 articles on a wide range of topics. His books include Super Crunchers: Why Thinking By Numbers is the New Way to Be Smart (2007), and Straightforward: How to Mobilize Heterosexual Support for Gay He is the author of a number of influential articles, most notably “Fair Driving: Gender and Race Discrimination in Retail Car Negotiations”, published by the Harvard Law Review, and “Filling Gaps in Incomplete Contracts: An Economic Theory of Default Rules”, published by the Yale Law Journal.

Ayres has been featured widely in the popular press, especially as a commentator on NPR’s “Marketplace” and as a columnist for Forbes. His research has also been featured on “Oprah,” “Good Morning America,” “PrimeTime Live,” and in Vogue and Time magazines.

Ayres holds a B.A. in Russian studies and economics and a J.D. from Yale, as well as a Ph.D. in economics from M.I.T. In addition to Yale, he has taught at Stanford Law School, Northwestern University School of Law, the University of Virginia School of Law, and the Moscow State Institute of International Relations. Last winter, he taught at HLS as the Robert B. and Candice J. Haas Visiting Professor.

Francis Biddle, the man for whom the lecture was named, is a 1911 graduate of HLS. He began his career as Private Secretary to Supreme Court Justice Oliver Wendell Holmes, and he served as America’s attorney general during World War II and as the U.S. member of the International Military Tribunal at Nuremburg.

The funds to support the Biddle Lectures were a gift from Francis Biddle’s widow—Katherine Garrison Chapin Biddle. A fervent proponent of civil rights, Katherine Biddle asked that the selection of lecturers reflect “that civil liberties and civil rights were of particular concern to my husband and thus particularly appropriate subject areas for the lectures.”